Various prior art devices are known which allow a user to insert a catheter/guidewire means into a body cavity or blood vessel so as to allow the user to deliver an inflatable dilatation balloon, cutting device or other therapeutic means to the area of need. In carrying out such procedures, which may be generally described as either angioplasty or atherectomy, the object is generally to effect the opening of a stenotic segment of a blood vessel.
Angioplasty uses a dilatation balloon positioned in an artery to dilate the arterial lumen at the stenosis. A typical angioplasty dilatation catheter is disclosed in Simpson et al., U.S. Pat. No. 4,323,071, incorporated herein by reference. The angioplasty device of the Simpson et al. patent includes an inflatable dilatation balloon which is attached to the distal end of a hollow catheter. The proximal end of the catheter is attached to a fluid source, providing fluid communication between the fluid source and the balloon.
To treat an arterial stenosis the dilatation balloon is introduced into the artery in a deflated state and guided through the artery over a guidewire to a position adjacent the stenosis. Fluid from the fluid source is then infused into the balloon via the catheter to inflate the dilatation balloon, which in turn dilates the lumen of the artery. The dilatation balloon is then deflated and removed from the artery.
While effective for dilating an arterial lumen at a stenosis, a balloon dilatation catheter such as that of Simpson et al. does not remove plaque from the artery. Also, balloon dilatation devices are often not effective with calcified lesions, long, tortuous lesions, or lesions that cannot be crossed with a guidewire. To address the shortcomings of angioplasty, a procedure termed atherectomy has been developed wherein a mechanical device cuts and/or ablades arterial plaque.
A stenotic segment of a blood vessel, i.e., a stenosis, presents a narrowed and often tortuous path through which the guidewire must be advanced, and in some cases the stenotic segment of the blood vessel may be almost completely blocked, i.e., occluded, with atherosclerotic plaque. A particular problem associated with angioplasty and atherectomy procedures generally is in moving the guidewire through or across a stenosis so that an inflatable dilatation balloon or a cutting device can be positioned within or adjacent to the stenosis. Accordingly, there is a need in the treatment of an occluded or narrowed blood vessel for a guidewire that can be easily moved through the stenotic segment of the blood vessel.
Furthermore, it has been found that the major reason a catheter procedure fails in the clinical setting is a result of the inability of a guidewire or a guidewire and a catheter, to cross a tortuous or stenotic (narrowed) path. Clinicians rely on the ability of such guidewires to transmit axial force, that is, "pushability," and their ability to follow the contours of the anatomy, that is, "trackability," to position these devices at the desired location. Often, when resistance is met, the clinician will shake or manually vibrate the proximal section of the catheter or guidewire to attempt to advance the device further. Although this technique is sometimes successful, if often fails because the movements are gross, the frequency is too low, the amplitude of vibration is too large and the transmission of axial force is very poor.
Uflacker et al., U.S. Pat. No. 5,243,997, incorporated herein by reference, discloses a hand-held vibrating device for vibrating a guidewire used in angioplasty and atherectomy procedures. The vibrating device taught there permits the guidewire to be more easily passed through a stenotic segment of a blood vessel. The Uflacker et al. vibrating device includes a case, an electric motor mounted within the case, and a clamp member coupled to the electric motor for releasably securing and vibrating the guidewire. In use the guidewire is threaded through a blood vessel to the site of a stenosis. The guidewire can then be clamped to the vibrating device, which is selectively actuated and manipulated to vibrate and push the guidewire through the stenosis.
While the device taught in the aforementioned U.S. Pat. No. 5,243,997 does provide some means for improving the mobility of a guidewire through a stenosis, nevertheless the remoteness of the vibrating means from the distal end of the guidewire which would come in contact with the stenosis, as well as the bulkiness of the vibrating means provided and the fact that it is not integral to the guidewire or catheter all present obvious limitations and serve to reduce the overall effectiveness of the vibrating means provided there. Moreover, such a construction would not be expected to be effective with catheters due to the length of catheters and the fact that the catheter material would dampen any vibratory motion.